Fix race between rmmod and cat /proc/kallsyms

module_get_kallsym() leaks "struct module *" outside of module_mutex which is
no-no, because module can dissapear right after mutex unlock.

Copy all needed information from inside module_mutex into caller-supplied
space.

[bunk@stusta.de: is_exported() can now become static]
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 14 deletions

diff --git a/include/linux/module.h b/include/linux/module.h
index 799930216626..58d5a10cdf0d 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -370,16 +370,14 @@ struct module *module_text_address(unsigned long addr);
 struct module *__module_text_address(unsigned long addr);
 int is_module_address(unsigned long addr);
 
-/* Returns module and fills in value, defined and namebuf, or NULL if
+/* Returns 0 and fills in value, defined and namebuf, or -ERANGE if
    symnum out of range. */
-struct module *module_get_kallsym(unsigned int symnum, unsigned long *value,
-                                char *type, char *name);
+int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
+                        char *name, char *module_name, int *exported);
 
 /* Look for this name: can be of form module:name. */
 unsigned long module_kallsyms_lookup_name(const char *name);
 
-int is_exported(const char *name, const struct module *mod);
-
 extern void __module_put_and_exit(struct module *mod, long code)
         __attribute__((noreturn));
 #define module_put_and_exit(code) __module_put_and_exit(THIS_MODULE, code);
@@ -527,11 +525,11 @@ static inline const char *module_address_lookup(unsigned long addr,
         return NULL;
 }
 
-static inline struct module *module_get_kallsym(unsigned int symnum,
-                                                unsigned long *value,
-                                                char *type, char *name)
+static inline int module_get_kallsym(unsigned int symnum, unsigned long *value,
+                                        char *type, char *name,
+                                        char *module_name, int *exported)
 {
-        return NULL;
+        return -ERANGE;
 }
 
 static inline unsigned long module_kallsyms_lookup_name(const char *name)
@@ -539,11 +537,6 @@ static inline unsigned long module_kallsyms_lookup_name(const char *name)
         return 0;
 }
 
-static inline int is_exported(const char *name, const struct module *mod)
-{
-        return 0;
-}
-
 static inline int register_module_notifier(struct notifier_block * nb)
 {
         /* no events will happen anyway, so this can always succeed */